Casting ferrosilicon



Patented Sept. 29, 1925.

UNITED STATES PATENT" OFFICE.

EMILE DABTE, OF WELLAND, ONTARIO, CANADA, ASSIGNO'R '10 ELECTRO METAL- LURGICAL COMPANY, A CORPORATION OF WEST VIRGINIA.

CASTING FERROSILICON.

No Drawing.

Province of Ontario, Canada, have invented certain new and useful Improvements in Casting Ferrosilicon, of which the following is a specification.

The invention relates to the casting of ferro-silicon, and particularly to the casting of pigs from metal containing less than about 20% of silicon. I

.Ferrosilicon of the composition referred to, for example the 15% alloy, is con-' veniently tapped from the furnace at 1500.

1600 (1, this temperature giving a good operation of the furnace. If, however, the.

pigs are poured at or about this high temperature, so much graphite is rejected by the metal as it cools in the molds or chills, that the pigs are covered with graphite and have cavities filled with it, making the handling of the pigs a dirty and disagreeable task.

Furthermore, if a pig casting machine with iron molds is used, the temperature of the metal as cast should be kept as low as possible to avoid'injury to the molds.

In accordance with my invention, tapping and casting are carried out at the respective high and low temperatures best adaptedfor the operation-s, and theaphite,

' instead of separating in the molds, is caused to separate in ladles where it blankets the molten metal and delays its coolin for a sufiicient time to permit its composition to be adjusted, and to give flexibility to the operation of the plant.

To these ends, themetal is tapped at a relatively high temperature into aladle, and is permitted to cool therein under the layer of graphite which formson its surfaceto the proper temperature for casting, the

. metal .beingpreferably agitated during the cooling. Because of the relatively slow cooling and the agitation, a more complete and uniform separation of the graphite occurs, and this graphite can be readily skimmed off, leaving a clean metal which rejects but little more graphitewhile cooling'in the pig molds.

I prefer to employ in the process a mixing ladle of sufficient capacity to hold several tappings from the same or difierent furf naces. The metal may be tapped from the furnaces into smaller ladles which are car- 'arrangedtobe rocked to agltate the metal Application filed July 19, 1923. Serial No. 652,630.

ried to and emptied into the large mixing ladle, located-in a convenient place with respect to the furnaces and to the pig bed or casting machine. The mixing ladle may be therei n,.or the metal may be stirred labor, orin any. other suitable Way.

With the arrangement just described, a more uniform composition of the product of the plant is possible. An abnormality of composition in-a single tapping is at-least partially corrected by the mixing of this tapping with others. In some cases, the abnormalities will be so related as to be compensatory, too high a silicon content balancing one which is too low. Also, additions may be made to the mixing ladle for the adjustment of the composition of the contained metal, for example scrap iron to bring down the silicon content, and high ferrosilicon or metallic silicon to increase the silicon content.

The blanket of graphite covering the metal in the mixing ladle and the use of addition-s to the metal are valuable for controlling the temperature of the metal. Loss of heat is prevented by the covering of graphite, and promoted by" removing the graphite. To expedite cooling, the graphite may be removed in successive portions as itseparates, while when slow cooling is desired, all the graphite will be left on the metal until the latter is to be cast. A small quantity of silicon, or a large quantity of 25% 'ferrosilicon, may have the same effect on the composition of the metal, but the latter will cool it much more. Any additions will of course be deferred so lon as minimum cooling of the metal is desire and as indicated above, the composition of the addition may be so chosen that it will by hand suitably affect both the composition and the I vention is es ecially adapted for the production of a loy of this approximate composition;

I claim:

1. Process of casting ferrosilicon containing less than about 20% silichn, which comprises tapping the metal from the furnace at a temperature considerably above the 4. Process of casting ferrosilicon lowest at which it can be readily cast, subcomprises mixing a plurality of tappings jecting the metal to controlled cooling to the of the metal beforecasting; and adding to I '5 rejected during cooling, and then casting the least one of the normal constituents ofjermetal. rosilicon, the added material being adapted 2. Process according to claim 1 in which in composition q y i ly the metal is agitated while ooling. affect both the composition and temperature 3'. Process according to claim 1 in which f h mixed metal- 9 the rate of cooling is controlled by manipu- In testimony whereof I aflix in signature. lation of the separating graphite, EMILE ARTE.

latter temperature, separating the graphite the mixed metal a material containingat- 

